THE
1996 EMISSION INVENTORY
As
part of the National-Scale Air Toxics Assessment (NATA),
USEPA prepared a comprehensive list of air toxics emissions
for the entire country in 1996. The emissions inventory
for New Jersey was briefly reviewed and revised by NJDEP
before being finalized by USEPA. Although there are bound
to be some errors in the details of a massive undertaking
such as this, a summary of the emissions inventory can
give us some indication of what may be the most important
sources of air toxic emissions in our state. As can be
seen from the pie chart below, Mobile
sources are the largest contributors to air toxics
emissions in New Jersey, with on-road mobile sources accounting
for 35%, and non-road mobile sources contributing 33%. Area sources represent 25% of the inventory (USEPA refers to this category
as "Area and Other" because it includes residential,
commercial, and small industrial sources). Major Point
sources account for the remaining 7% of the inventory. Major
Point sources are defined by the Clean Air Act as
facilities that emit more than 10 tons per year of a single
hazardous air pollutant (HAP) or 25 tons per year of all
HAPs combined.
Sources
of Air Toxics in New Jersey
Based on U.S.EPA's 1996 Air Toxics Inventory
USEPA also compiled an air toxics emissions inventory
for 1990 as part of its Cumulative Exposure Project
(CEP): "An
Sab Report: The Cumulative Exposure Project"
(Pdf Format) "Modeled
Outdoor Concentrations of Hazardous Air Pollutants: Analysis
of Data from the Cumulative Exposure Project for the Urban
Area Source Program" (Pdf Format). The CEP results
were discussed on this website previously, and can still
be accessed by clicking here.
However, USEPA emphazises that the methods used to conduct
the 1990 and 1996 emissions inventories are different,
so that the results for the two different years cannot
be compared directly.
COMPARISON
OF EMISSIONS BY COUNTY
When
the emissions estimates are broken down by county, it
is evident that the areas with the largest air toxic emissions
are generally those with the largest population in the
smallest space. This is directly related to high levels
of vehicle use, solvent use, and other population-related
types of activities in those counties.
Estimated
Air Toxics Emissions for New Jersey, by County
Based on U.S.EPA's 1996 Air Toxics Inventory
COMPARISON
OF EMISSIONS BY SQUARE MILE
The
chart below shows the amount of emissions in tons per
year per square mile, which is primarily related to population
density. Hudson County is the smallest county by area,
but by far the most densely populated (12937 people per
square mile, compared to the statewide average of 1125
people per square mile).
Estimated
Air Toxics Emissions Density for New Jersey, by County
Based on U.S.EPA's 1996 Air Toxics Inventory
IN
NATA, THE POINT, AREA, AND MOBILE SOURCES ARE GROUPED
IN THE FOLLOWING WAY:
Major
Point Sources: A point source is a stationary facility
or process that emits a significant amount of air pollution
during manufacturing, power generation, heating, incineration,
or other such activity. For NATA, USEPA called this category
"Major Sources," and included in it just those
sources which emit at least 10 tons per year of any one
hazardous air pollutant (HAP), or at least 25 tons per
year total of any HAPs. Major point sources include power
plants; refineries; municipal waste incinerators; toxic
waste transfer, storage and disposal facilities (TSDFs);
TRI sources (facilities that are required to report their
emissions under the Toxic Release Inventory program);
and other sources that have reported emissions under other
state and federal programs.
Area and Other Sources: These are small sources of
air pollution which by themselves may not emit very much,
but when their emissions are added together they may account
for a sizable portion of the total emissions of air toxics.
In NATA, USEPA refers to this category as "Area and
Other Sources," and includes small industrial sources
that fall below the "major source" threshold.
Area sources are often too small or too numerous to be
inventoried individually. The following are grouped under
area sources in NATA:
- Industrial
processes such as chromium electroplating, surface coating
of cans and paper, metal parts cleaning, metal recycling,
small chemical manufacturing plants, and bakeries
- Consumer
products, such as personal care products, household
products, adhesives and sealants, automotive products,
and coatings such as paints.
- Residential
heating and fuel use
- Pesticide
use
- Prescribed
burns, and forest and wildfires, and structure fires
- Gasoline
stations
- Dry
cleaners
- Institutional
and commercial heating
Mobile
Sources are divided into two categories:
- On-road
mobile sources are vehicles found on roads and highways,
including cars, trucks, buses, and motorcycles.
- Non-road
mobile sources include aircraft, trains, lawnmowers,
boats, dirt bikes, construction vehicles, farm equipment,
etc.
BACKGROUND
CONTRIBUTION
Some
of the 33 air toxics evaluated in NATA are no longer emitted
in significant quantities, but levels in air persist from
past emissions. For a discussion of backround concentrations,
click here.
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